From the weight of the lens (1000g) I had expected a much larger package. But as you will see soon, this lens is not so much bigger than e.g. my Sigma 10-20mm, but because of all the bulging glass built into this (14 (!) lenses in 11 groups), it's the heaviest lens in it's class!

Now onto the next test: Shooting against a 50W halogen-spot as contra-light to check for flare/ghosting. I tested at different focal length and apertures.
All I can say: very impressive results! See the following images...

First the worst I could get (@14mm f/8 ): there is one clear reflection of the bulb and another faint spot. To the right at f/8 and 23mm there is almost nothing to be seen:

Next test is at f/2.8 and 14mm and 24mm

You can click through to the originals at flickr where I've marked the spot(s) with notes.

You wanted the low-down on technical data? Here they are (figures in brackets are from the only other FF/FX ultra-wide-angle zoom, the Sigma AF 12-24mm 4.5-5.6 EX DG Asp HSM IF):
Size: 98x131.5mm (vs. 87x100mm) = even bigger than the already hefty Sigma Weight: 978g (vs. 615g) = even fatter than the already fat Sigma This zoom now is the biggest, fattest ultra-wide zoom. Optics: 14 lenses in 11 groups (vs. 16/12) = better than the Sigma Closest focus distance/max.magnification: 0.27m / 1:5.8 (a little better than the Sigma) Filter-mounting: no way, not even rear mounted even worse than with the Sigma No IS = not so important (I'll come back to this later)
AF-S, so works on D40/x-bodies , easy manual-focus override (just turn the focus ring) (same as Sigma) Covers FF/FX-sensors and goes to F/2.8 This is also the reason for the huge size/weight and the price-premium of this lens. 14mm on a FX-sensor body is equivalent to 9.5mm DX lens (on a DX-body)! But the Sigma goes even wider: 12mm (equivalent 8mm DX-lens on DX-body) but has only F/4.5 as max aperture.
Comes with a nice lens-bag (see above) and the lens-shade is built-in (same as Sigma)
Price: around 1700€ (incl. 19% you-know-VAT) = the most expensive (topping even the Nikon DX 12-24mm and FX 17-35mm) And the rear lens-cap is standard Nikon, not the cr*ppy one on the Sigma
The zoom-ring is near the camera-body, the focus-ring in front. Why that is the reverse to other nikon-zooms is beyond me (but it is the same as the Sigma)
No dof-marker (same as Sigma) Only switch on the lens is the "M/A vs M" switch (no switch on the Sigma)
And finally: It's a G-lens, so no aperture-ring here

Now let's proceed to the famous Siemens-stars and what they will tell us with respect to the resolution-power of the Nikon 14-24mm vs. the Sigma 10-20mm.
I shot a 5-target subject on a flat, mirror-covered surface, auto-focus on the middle target, like that:

This means the following:
- If any of the lenses I test has field curvature, that will not be distinguishable from the "natural" drop in resolution at the corners. I don't shoot focus brackets to find a point where the corners are sharpest.
- If AF fails so be it. As I'm no manual-focus-man I have to rely on what the camera makes out of the target. That said, all lens-tests so far have been made with the same D80 body. And normally you can immediately identify one bad focus image out of a series. But should micro-focus not be spot on, that's it then. In these cases you should get a quite pronounced increase in centre-sharpness when stopping down
- If the camera is mis-aligned (not exactly perpendicular to the target) you should see quite different resolution in the 4 corners. But the mis-alignement should hit both lenses the same way at the same focal lengths, as I didn't change the position of the tripod for a single focal length.
- If a lens has a decentering defect, you should see quite different resolution in the 4 corners. If that sounds like above, you're right. But: normally two lenses don't have the same decentering defect. So when one lens has differing sharpness in different corners and the other lens has not (at the same focal lengths and tripod/camera position), then this lens is decentered.
- Resultant from the above two critical points I use the best of the corner resolution results to avoid any discussions about "not an equal playing field" and comment on it. You can view all corners of all my Siemens-star shots at flickr in full resolution and make up your own mind if you care.
- These 5 targets are good for resolution testing in that the stars have a grey disk in the middle, the diameter (and form) of which is directly (reverse) proportional to the resolution of this lens at this spot: I.e. a 30% smaller diameter of the grey disk equals 30% better resolution. All my lens-reviews are comparable as they use the same target, but my measures of the grey disk may differ from yours, as they depend on the pixel-pitch of your monitor. The measures I give are taken from a 21" 1600x1200 monitor!
- I try to avoid camera shake as I shoot from a tripod using a remote control and flashlight. That are perhaps not the very best conditions but should be pretty stable
- The targets are at a magnification of around 1:50. That is far away out to give you a good approximation of far-field performance.
- For the pics that I present here I've done a RAW>JPG conversion with CaptureNX 1.3.1 at standard sharpening (not altered from what the body was set to). Be aware though that I don't do this conversion with all my Siemens-star shots at Flickr. The other images being standard large jpegs directly off the camera. There are people saying that the RAW-conversions are sharper than the JPGs directly from the camera.((EDIT: After looking closely how the conversion from RAW in CaptureNX was different from the in-camera conversion I decided to stay with the in-camera converted JPGs. So forget about the last paragraph))

What I will present you with in the next post is a series of 100% crops linked to the original pic's homepage at Flickr. We have three comparable focal lengths: 14mm, 17/18mm and 20mm (unfortunately I didn't match the 17mm on the Sigma, but that has no influence on the reading of the grey disk)
For each focal length I'll show you 4 pics:
(1) the Nikon wide open @F/2.8 and then (2) closed to the widest aperture the Sigma could muster (F/4-F/5.6), then (3) the Sigma wide open and (4) the Sigma at F/8.
I need not show you the Nikon at F/8 as this is not necessary (you'll see). All apertures and focal lengths are at Flickr for the Nikon and the Sigma.

To complete the series I'll include the 24mm Nikon results and the 10mm Sigma results plus some comparison of the Nikon at f22 to show you how the res deteriorates due to diffraction to satisfy your every appetite.

Focal length = 14mm.............Nik F/2.8........................Nik F/5.6........................Sig F/5.0........................Sig F/8.0.............
The diameter of the grey disk is around 7-8mm. Closer to 7mm for the Nikkor and closer to 8mm for the Sigma

Focal length = 20mm.............Nik F/2.8........................Nik F/5.6........................Sig F/5.6........................Sig F/8.0.............
The diameter of the grey disks are (from left to right in mm): 8, 7-8, 8, 8.

Overall the centre-sharpness is not too revealing, both lenses play on a very high sharpness- and contrast-level with a small advantage for the Nikkor. Only at 17mm F/2.8 the Nikkor seems a bit softer than at the other settings.
Let's see whether this pertains for the corner-crops too.
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Addendum: The color-shift has nothing to do with the lenses! It's only a shifting mixture of incandescent- and flash-light with different apertures...

Here we go! Part 2 = 100%-crops from the corners. Looking at all four corners of each pic revealed slightly different results and I always used a crop from the best corner. In the case of the Nikkor I didn't see much of a difference apart from that 17mm /2.8 shot where the lower left corner was better than the upper rigth corner. To give you an impression of the differences see both crops from the Nikkor 14-24mm @ 17mm F/2.8:
Lower left= Upper right=See what I mean? In case of the Sigma I took the lower right corner @14mm, the upper left corner @18mm and the upper right corner @20mm.

Focal length = 14mm.............Nik F/2.8........................Nik F/5.6........................Sig F/5.0........................Sig F/8.0.............
The diameter of the grey disks are (from left to right in mm): 8, 8, 9-10, 9-10. The Sigma shows slight astigmatism.

Focal length = 20mm.............Nik F/2.8........................Nik F/5.6........................Sig F/5.6........................Sig F/8.0.............
The diameter of the grey disks are (from left to right in mm): 9, 9, 9, 8-9.

So in general the res in the corners is 10-20% lower than centre-res. The Sigma taking a hit at 14mm but other then that keeping up with the Nikkor quite nicely. What is astonishing from the Nikkor is that the IQ does not deteriorate visibly at full open aperture, that is in most cases 2 stops brighter than the Sigma. A remarkable feat!

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Sorry, no link-through from the crops today. You can find the originals via the above links. All images are properly labelled...

Now let's finish the resolution lab-test off with the remaining focal lengths: 24mm on the Nikkor (and 10mm on the Sigma for completeness).
First the Nikkor at 24mm and F/2.8, F/5.6, F/11 and F/22 (100% centre-crop):
The grey discs are 7-8mm, 7mm, 7mm, 9mm as the influence of diffraction kicks in.

Now the same with 100% corner-crops:
The grey discs are 9mm, 8+mm, 8mm, 10+mm.

Finally the Sigma at 10mm and F/4, F/5.6 and F/8(100% centre-crops in the first line then the corner-crops):
The grey discs are all at 9mm.

The grey discs are 10mm, 9mm and 9mm.

And no, this is not light fall-off from the lens' vignetting! It's just uneven lighting

Next up is a shoot-out in the wild to show you some real-life delta between the lenses with respect to sharpness and fringing...

Ok here comes the reality check. Shooting in the woods against lead-grey sky. Both lenses set to 14mm at F/5.6 a photo like this:
Very exciting subject , but you can see, what I'm aiming at: focus to infinity and have some very fine structures against bright light. That will tell us something about sharpness, contrast and color-fringing...
First set of comparisons is a 100% crop from the upper left corner, first line the Nikon 14-24mm, second line the Sigma 10-20mm. To the left you'll see the crop from the large normal JPG as it came out of the camera, to the right you'll see the JPG as processed in CaptureNX without any further tweaking. And you can clearly see how CaptureNX does away with the dreaded color-fringing that occurs on both lenses, although I might say the Nikon suffers more from CA than the Sigma.
Nikon:

Sigma:

And I'm pretty sure that you see the Nikon's glaring CA (left, which CaptureNXcleans up pretty well) and would also give it just a little less sharpness than the Sigma

But let's have a look down at the ground. Both of the following 100%-crops from the lower right side were processed from the original NEF with CaptureNX. To the left is the Nikkor, to the right the Sigma:

You wouldn't believe the difference now. Here the Nikkor is the clear winner. And the crop is not even in the extreme corner of the image. But it's not only sharpness that makes the Nikkor-crop superior, it's also contrast. So obviously the lower right corner of the Sigma is not it's sharpest (which can also be proven with the star-targets). But the Sigma is also behind the Nikkor with respect to contrast.

To test this, I increased brightness of the Sigma-shot so that the sky resembles the brightness of the Nikkor-shot. Then I pixel-peeped at RGB-values in the darker parts on the bottom to find that the Nikkor-shot had at least a 1-stop higher contrast. This can certainly be compensated for by upping the contrast on images shot with the Sigma, but some shadow details will be lost in high contrast situations.

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To give you a summary of the findings so far:
If you forget that the Sigma is a DX-lens and has a variable max aperture of F/4.0-5.6, it fares quite well against the Uber-wideangle from Nikon. With respect to sharpness it is only marginally weaker with a little sore spot in one corner and some deterioration of contrast in stark contra-light (also remember the flare-problems of this lens).
The Nikkor impresses so far with superb sharpness even wide open, very good contrast even in strong contra-light situations and it can fill an FF/FX-sensor certainly well above 30MPix. This all has it's price (and weight) though, but in the end you'll get what you pay for.

Well, here's a tough nut to crack: The Nikkor 14-24mm does not really behave like a F/2.8 lens! How so?
Now I've done the following: Auto-Iso=OFF, frame a well and constantly lit white door, focal length=24mm, MF to infinity, manual expose a series from F/5.6/4.0/3.3/2.8 with shutter speeds in (1/sec) of 15/30/45/60. Well at F/3.3 the prob starts and F/2.8 came out clearly darker than the other exposures although the EV is all the same Then tried same with my 50mm F/1.4D for F/2.8/2.0/1.7/1.4. Same here: from F/1.7 the image becomes darker and F/1.4 is another step darker.
From looking at it looks similar to the light fall-off (no,not vignetting!) as on the 14-24mm.
So what is the explanation? And - as I found this "underexposure" at aperture-priority - why is this not accounted for at automatic exposure??

Following are the exposure-histograms in LightRoom:
.
Compared to my reference chart of 1/2-stop-histograms this looks like a 1/4-stop loss @ F/3.3 and a 3/4-stop loss @ F/2.8.
So you and your automatic is almost underexposing 1 stop when you use the lens wide open Quite a disappointment for such an expensive f/2.8 lens being effectively only F/3.7...
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Btw. Someone has an explanation for the histogramm getting broader the more open the aperture is? Loss of contrast??

And I'll add another post for real-life contra-light performance. The following shot was taken against the glaring winter-sun:
If you look closely in the lower right corner or click through to the large original, you'll see a rainbow-colored ring there.
Fantastic!
With the next one the sun is not directly in the pic but was still shining directly into the lens:
When you click through I've noted the 4 smallish spots in the pic.

Just an update on the question of max open aperture:
Nikon Germany knew nothing about such a case and suggested to send the body in to a service point. Service point said the same thing.
So let's assume that the lens really is an effective F2.8 until I can report back with results from the service...